Thread-cutting tool



Oct. 9, 1951 c, PULLQN 2,570,483

THREAD CUTTING TOOL Filed May 7, 1948 Jig V////////////%m 12 Patented Oct. 9, 1951 Russell 0. Pullon; Los Angeles, Calif.', assignor to Mimita A. Cogliandrmlmshngelea Calif.

I Application-May 7, 1948, Serial No. 25,727

I My invention relates working machine cutting tools, and particularly to tools for cutting V threads either by traversing the work and tool relatively to one another as when forming a rack or by feeding the tool into the work to cut a continuous helical thread thereon. The invention will be specifically described with relation to this latter operation by way ofexample only since the invention i not limited to this application.

In cutting V screw threads, for instance, the cutting tool is subject to much vibration due to the out being made on both edges of the V, necessitating .repeated cuts to obtain a satisfactorily to improvements in metal l a rotated bar while moving the tool axially alon fine finish, and repeated adjustment of the tool holder. It i an object of my invention to provide a cutting tool by which a fine finish cut may 1 be given by adjustmentof'the cutting tool without requiring adjustment of the tool holder.

It is another object of my invention to provide a V thread screw cutting tool which can be used to give a finish cut after the full depth has been cut by adjusting the cutting tool to out along one edge while relieving the pressure on the other .edge of the tool and then similarly adjusting the other edge of the cutting tool without changin the adjustment of the tool as a Whole.

may be adjusted accurately between predetermined limits without adjustment of the tool as a whole, the construction of the tool being simple and rugged and therefore long-wearing and satisfactory in service.

Still further objects and features of my invention will hereinafter appear from the following description taken in conjunction with the accompanying drawings in which is illustrated a preferred form of my invention but it is to be understood that various changes and modifications of parts may be made in the described form of the invention without departing fromthe scope of the invention as intended to be defined by the appended claims.

In the drawings:

Fig. 1 is a plan view of the tool;

Fig. 2 is a cross section on the line 2-2 of Fig. 1;

Fig. 3 is an end elevation of the tool looking in the direction of arrow 3 in Fig. 2;

Fig. 4 is a fragmentary cross section on the line 4-4 of Fig. 2 drawn to an enlarged'scale;

Fig. 5 is a cross section on the line 5-5 of Fig.

4 Claims. (ores-'98) Fig. -6 is a fragmentary detail showing the cutter, fully entered and centered in the material;

Fig. "7 is a fragmentary detail. showing the cutter adjusted to give a finish cut'to the right hand face of the thread;

Fig.8 is a similar view to Fig. 7, but showing the cutter adjusted to give a finish cut to the. left hand face of the thread and Fig. 9 is a view similar to Figs. 7 and 8, but showing the cutter advanced to finish off the bottom of the thread.

In the drawings thenumeral l2 indicates the shank rectangular in cross section of the tool which is preferably provided with an offset head v I4 pivotally mounted on the head bya shouldered l2aflcut away to receive a cutter holding block stud 6. The head is also bored at ill to receive fastud projecting from the underside of block .14 between pivot l6 and its rearward end. Stud 20 i6 is machined to'provide an opening 22 having parallel vertical edges, and the opening is Qch'amfered to produce a substantially straight The shank of the tool is length and a rod 24' is accurately journalled in the drilled hole with its forward end extending "line engaging surface" 24.

'which may .be of the order of .001".

drilled throughout its into the opening of stud 2U. The forward endof the rod is ground to provide a circular cam 25 off center by the depth of finish cut to be given, The cam will engage with the straight line surface 24 of the stud 20 as shown in Fig. 5. The rearward end of rod 24 is immovably secured to a small strip." held for rocking movement on a stud 30 screwed into the end of the tool shank, strip 28 having an accurate opening 32 formed therein to permit of a limited rocking movement relative to the stud 30, the head of which abuts the outer surface of strip 28 and holds rod 24 against removal. A knob 34 is secured to strip 30 forming a crank therewith bywhich strip 28 and rod 24 may be rocked about the longitudinal axis of the latter.

Three accurately positioned conical depressions 36a, 36b, 360 are formed on the inner face of strip 28 at the same distance from the axis of rod 24, depression 36b being placed in the vertical plane in which the axis of rod 24 is located, while depressions 36a and 361) are located at points corresponding to the maximum off-center position of the cam '26 to left and right, respectively, which will'throw the right and left cutting edges of the tool respectively against the work.

A conical ended detent 36 is mounted in a hole 7 38 drilled in the shank l2 with its axis at the same distance from the axis of rod 24 as the spacing of conical depressions 36a, 36b, and 36c from the axis of the rod vertically above and parallel to the axis of the rod 24 relatively stiff helical Spring 40 is positioned under compression between the inner end of the detent and the end of the hold-.38; The arcuate opening 32 is long enough to permit strip Mite-bierockeduill ciently to enable detent 36 to fully enter depressions 36a, 36b and 360 and hold the strip in the exact predetermined limit positions.

The cutting bit 42 may be mounted in any suitable manner in head [4,. as shown The head is provided with a grocvelasomewhat wider than the bit 42, a wear plate 16 being positioned between one side of the groove and of the bit and the bit is clamped in position by threaded studs 48 engagin through threaded holes in the head against the wear plate. Both the block [4 and cutter bit are preferably iven a radius at the rear and fit with a similar radius machined at the forward end of the; shank in order to secure su ort therefrom.

In use, the cutting tool is given a contour such that after the finishing cuts have been made the lateral faces of the thread will have been cut .to accurate dimensions and a final cut is made a tool holder pivotall mounted at one end of ,the shank for displacement to an equal extent on opposite sides of a center line; a rod extending through a longitudinal bore in said shank from the end thereof; a cam mounted at the opposite 'end of said rod and engaging with said tool holder at a point spaced from the pivotal axis thereof, making of said rod being effective to cause said cam to lpivotally move said tool holder; means mounted at the rear end of the rod by which it may be rocked about its longitudinal axis; and means for limiting the extent of the movement of said latter means.

2. A thread cutting tool comprising: a shank; a tool holder pivotally mounted at one end of the shank for displacement to an equal extent on opposite sides of a center line; a rod extending through a longitudinal vbore in said shank from theend thereof; a cam mounted on the-opposite end of said rod; a pin depending from said tool 4 holder into a recess in the shank, said pin being apertured to receive said cam; means mounted at the rear end of the rod by which it may be rocked about its longitudinal axis; and means for limiting the extent of the movement of said lat- 'the shank for displacement to an equal extent on opposite sides of a center line; 'a rod extending through a longitudinal bore in the shank from the end thereof a cam mounted at the opposite end of said rod and engaging with said tool 7 holder at a point spaced from the pivotal axis thereof, rocking of said rod being effective to cause said cam to pivotally move said tool holder; a plate secured to the end of said rod;

means holding said plate for movement in the plane of the vertical end of the shank and for limiting the extent of said movement; a handle secured to said plate by which the latter may be moved to rock said rod about its longitudinal axis; and means for holding said plate in a celltralposition, and in predetermined positions located to each side of said central position.

4. A thread cutting tool as set forth in claim 3, and in which the means for holding said plate in position comprise a central conical depression in the inner face of said plate and a conical depression on each side of said central depression and equally spaced therefrom; a conical end plunger mounted in a bore in said shank on the vertical center line thereof, and a spring urging said plunger into engagement with whichever one of said recesses is aligned with the plunger by operation of the handle.

' RUSSELL c. PULLON.

REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS 

